Process of making projection-screens.



L. J. AUERBACHER. PROCESS OF MAKING PROJECTION SCREENS.

APPLICATION FILED APR. 8, 19l5.

l gwfifiw. Patented Nov. 28, 1916.

LOUIS J'. AUERBACHER, 01E NEWARK, NEW JERSEY, ASSIGNOR TO THE FEDERAL SCREEN CORPORATION, 015 NEW -gOJRK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OJE MAKING PROJECTION-SCREENS.

Specification of Letters fatent. Patt fled Nov, @fi, T911115,

Application filed April 8, 1915. Serial No. 20,049.

To all whom it may concern:

DBe it known that T, LOUIS J. AUERBACHER, a citizen of the United States, residin at r Newark, in the county of Essex and tate of New Jersey, have invented certain new and useful Improvements in Processes of Making Projection-Screens, of which the following is a specification.

This invention relates to screens for use .in displaying pictures by means of a magic lantern or moving picture projecting apparatus, and its novelty consists in the successive steps of the method of making the screen and the resulting novel product.

In the accompanying drawing-Figure 1 is a vertical sectional view throughthe improved screen. Fig. 2 is a face view of a portion of the same.

Screens upon which to display pictures of the kind described are usually so arranged that the source of light impinges upon a miniature representation of the picture intended to be displayed, passes through a suitable lens system, and the rays,

condensed or dispersed as the case may be, are then pro ected against an'opaque screen,

whence they are reflected to the eyes of the spectators. The screen which is the subject matter of this application is of a difierent character. It is composed of trans parent or semitransparent material and it is intended that the rays of light striking upon the screen shall be transmitted there-v through and thence reach the eyes of the spectators, the light falling upon the screen 4 from the opposite side being more or less refracted, dispersed, or absorbed by ,the nature of the surface facing the spectators.

The basis of the screen to be made is any suitable reticulated material in the form of a thin sheet, such as woven wire cloth or bolting cloth or the like.' This is placed upon a suitable surface such as a flat table and the upper surface is then coated with a film of transparent material. For this purpose, I prefer to employ a solution of acetate cellulose or nitratecellulose or pyroxylin in a suitable volatile solvent such aslacetone or a primaryolefin such as is described in Letters Patent ofthe United States No. 972,958. The solution is pref erably applied'with a brush, although if sufficiently dilute the solution may be flowed upon the surface of the reticulated material, but this requires considerable skill and solvent.

I prefer on that account to make the appli- 621 1310118 by means of a brush. The solvent 1s then removed. This may be accomplished by natural evaporation if the ventilation is good, or the screen may be subjected to the act1on of a current of hot air, or any other means may be employed to remove the volatile vapors coming- 0H from. the.

siderable, both for the solvent and the thing dissolved, but according to my present knowledge acetate cellulose dissolved in acetone gives good results. a

As stated above, in use, this screen is employed as a receiving surface for a projected image but it is interposed between the source of light and the spectator. When the screen is made of one layer of fabric and one layer of film as above described, either the film side or the fabric side may be presented toward the spectator, but I prefer the latter arrangement, as the outside light or daylight'seems to be absorbed better when the screen is so arranged.

The above is the simplest method of'm-aking the screen in its simplest form. After .forming a coating of film on one side ofthe fabric as above described, I continue further and turn it over and coat its opposite side in precisely the same manner as before, so that the screen will then consist of a sheet of fabric between two sheets of substantially transparent films. In such case. there is of tion of the light from the side of the screen to be presented toward the spectator by forming such surface of a sheet of film which shall present anenormous number of con-' -cave interruptions of its continulty, so that Whileit may appear to be substantially con-.

tinuous, the surface is nevertheless broken up into lenticular parts or portions which serve as refractive media. In the'making of a film of this character-,1 first make a mold of plaster or glass or similar material provided with convexities and concavities so character described. I then fiow or brush the film-making material onto such mold land after a suitable thickness has been applied, remove the solvent as before. Before the film has completelydried, I apply the sheet of reticulated material to its upper surface and it adheres thereto, so as to form an integral portion thereof. The result of course is a screen having a rear side of fabric or reticulated material and a front side of refracted interruptions. I may further continue the process by adding an additional sheet of film at the rear of the reticulated material. When made with such a refractive surface, that side should in use be presented toward the spectator.

I claim:

23 1. The art of makinggafprojection screen which consists in forming upon the surface of a sheet of transparent film-like material a series of refractive optical elements, and attaching to the opposite side of the sheet a sheet of suitable reticulated material.

2. The process of making a projection screen which consists in forming upon the surface of a sheet of trans nlrent film-like material a large number of interruptions of its continuity whereby the refractive power 30 of such surface is promoted, attaching to the opposite surface thereof a sheet of suitable reticulated n'iaterial, and providing at the back of the latter sheet a second sheet of film.

In testimony whereof I affix my signature in presence of a witness.

LOUIS J. AUERBACHER. Witness:

ALBA L. MILLER. 

